<!DOCTYPE html>
<html>
  <head>
    <meta charset="UTF-8">
    <title>Document</title>
  </head>
  <body>
    <script>
      // 同时声明多个变量，不赋值
      var myName, age, email;
      // 同时声明多个变量，并赋值 
      var myName = '小明',
          age = 18,
          email = 'xiaoming@localhost';
    </script>
  </body>
</html>